Construction work and method of production

ABSTRACT

The construction work erected in front of a pre-existing wall comprises a facing standing along a front face of the work, a fill occupying a gap between the facing and the pre-existing wall, and a retention system extending into the fill for keeping the facing in place relative to the pre-existing wall. The retention system comprises first stabilizing elements attached to the pre-existing wall and extending into a first region of the fill, and second stabilizing elements connected to the facing and extending into a second region of the fill. The first and second regions have a common part in which forces are transmitted between the first and second stabilizing elements by the fill material.

BACKGROUND OF THE INVENTION

The present invention relates to the construction of civil engineering works using stabilized fill techniques.

The works to which the invention relates may have a variety of uses such as, for example, for widening traffic lanes, for extending a constructible space, for preventing deterioration, erosion or collapse of stone or rock walls, or else for creating an attractive solid mass. In general, they comprise a fill placed vertically or approximately vertically against the solid mass or structure supporting the traffic lane or the constructible space, or the wall of which is deteriorating. The vertical wall to the front of the fill consists of a facing connected to the pre-existing structure.

This pre-existing structure may have irregular geometrical characteristics.

Thus, the construction of a fill, whose facing has to be straight with a linear shape, requires that the irregularities on the front side of the pre-existing structure be taken into account. This is because the width of the fill would have to vary both in the height direction and in the length direction.

To avoid this difficulty, one solution consists in making the wall against which the fill will bear as plane as possible. Thus, the members connecting the facing to this wall will have roughly the same length. The residual imperfections in the wall are then remedied by pragmatic adjustments to the lengths by empirical time-consuming methods.

Another solution consists in providing openings in the facing elements so as to pass thereinto the connection members anchored to the wall of the pre-existing structure. The connection members are then tensioned by means of rams and then anchored into the facing. This solution requires relatively substantial handling and a relatively long time, and accordingly increases the cost of constructing the fill.

An object of the present invention is to propose another solution, which allows simple, rapid, and therefore inexpensive, construction of a fill having a facing of regular shape, typically a plane shape, to the front of a pre-existing wall whose shape may be irregular.

SUMMARY OF THE INVENTION

The invention thus proposes a construction work erected in front of a pre-existing wall. The work comprises a facing erected along a front face of the work, a fill occupying a gap between the facing and the pre-existing wall, and a retention system extending into the fill for keeping the facing in place relative to the pre-existing wall. According to the invention, the retention system comprises first stabilizing elements attached to the pre-existing wall and extending into a first region of the fill, and second stabilizing elements connected to the facing and extending into a second region of the fill, said first and second regions having a common part in which forces are transmitted between the first and second stabilizing elements by the material of the fill.

The friction between the stabilizing elements and the fill material ensures that forces are transmitted by the fill material in the common part between the first and second regions. Such a way of transmitting forces has already been proposed in the case of retaining walls (WO 2005/040506). In the application considered here to the construction of a new wall in front of a pre-existing wall, the profile of which may be irregular, this way of transmitting the forces ensures that the facing is held in place relative to the pre-existing wall.

A major advantage is that the relative independence between the first and second stabilizing elements makes it possible for the first elements to be attached to the pre-existing wall without the particular concern for the relative alignment of the anchoring points relative to a vertical plane. The first elements will penetrate sufficiently into the fill in order to obtain sufficient thickness of the common part between the first and second regions without requiring a precise adjustment of their length. This results in great simplification in stabilizing the fill and in constructing the work.

In preferred embodiments of the work according to the invention:

-   -   the facing comprises prefabricated elements in which the second         stabilizing elements are partly embedded;     -   these prefabricated elements are preferably made of concrete,         the second stabilizing elements being in the form of flexible         synthetic reinforcements each having at least one part cast in         the concrete of one of the prefabricated elements;     -   this cast part of the flexible synthetic reinforcement follows a         loop in the prefabricated element so as to have two segments         that project into the second region of the fill, the loop         preferably being placed in the prefabricated element so that the         two projecting segments of the flexible synthetic reinforcement         emerge from the facing into the fill at vertically spaced         positions;     -   the second stabilizing elements comprise geotextile layers         extending into the second region of the fill. Preferably, the         work then comprises geotextile sheets folded so as each to have         a front part extending over the front face of the work and         forming a portion of the facing, and two layers folded back from         said front part and extending approximately horizontally into         the fill in order to form two of the second stabilizing         elements;     -   the second stabilizing elements comprise metal reinforcements         attached to the facing and extending into the second region of         the fill;     -   there is substantially no direct contact between the first         stabilizing elements and the second stabilizing elements;     -   the first and/or second stabilizing elements are flexible         synthetic strips; and     -   the first stabilizing elements in the form of flexible synthetic         strips are placed along zigzag paths in the first region of the         fill.

Another aspect of the invention relates to a method of constructing a work in front of a pre-existing wall, comprising the steps of:

-   -   erecting a facing along a front face of the work, delimiting a         volume to be filled;     -   positioning a retention system in a gap between the facing and         the wall for holding the facing in position relative to the         wall;     -   providing fill material into said gap; and     -   compacting the fill material.

According to the invention, the retention system comprises first stabilizing elements attached to the wall and extending into a first region of the fill, and second stabilizing elements connected to the facing and extending into a second region of the fill, said first and second regions having a common part so that, after fill material has been introduced and compacted, forces are transmitted between the first and second stabilizing elements by the fill material located in said common part.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view in lateral section of one example of a construction work according to the invention.

FIG. 2 is a schematic top view of the construction work shown in FIG. 1.

FIG. 3 is a schematic view in lateral section of an alternative embodiment of a construction work according to the invention.

FIG. 4 is a schematic top view of the construction work shown in FIG. 3.

FIGS. 5 and 6 are partial perspective views of other embodiments of a construction work according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 to 5 illustrate the non-limiting application of the invention to the construction of a straight vertical wall to the front of a solid terrain mass 1 on which a road 2 has been constructed. The mass 1 has an irregular profile on its front side.

The front side of the construction work has a facing 3, for example made of juxtaposed prefabricated elements 4 of reinforced concrete. A compacted fill 5 fills the gap between the facing 3 and the wall formed by the front side of the mass 1.

FIGS. 1 and 2 show stabilizing elements 6, 7 buried in the fill 5 in order to hold the facing 3 in position relative to the mass 1.

In the example shown, the stabilizing elements 6, 7 are linear elements, such as reinforcements made of rolled steel or geotextile strips. The elements 6 are anchored to the face on the front side of the mass 1 by means of conventional anchoring members 8, such as for example expansion bolts, masonry anchors or nails. The elements 7 are fastened to the rear of the facing 3, which is for example provided with metal rings for accommodating them.

In the example shown in FIGS. 1 and 2, the stabilizing elements 6, 7 are placed approximately in horizontal planes and perpendicular to the facing 3. The elements 6 attached to the mass 1 stabilize the fill 5 in a region Z1 that extends over more than half the width of the filled gap. Likewise, the elements 7 attached to the facing 3 stabilize the fill 5 in a region Z2 that extends over more than half the width of the filled gap. These two regions Z1, Z2 thus overlap in a common part Z′, the thickness of which is intended to be sufficient for the friction between the elements 6, 7 and the cohesion of the fill material 5 to ensure that the facing 3 is held in position relative to the mass 1. In this common part Z′, the material of the fill 5 is very strong because it is stabilized by the elements 6 and 7. It is thus capable of withstanding gravitational forces and forces due to the application of possible loads on the top of it.

Depending on the dimensions of the work, on the materials employed and on the spacing between the stabilizing elements 6, 7 (which spacing may be reduced as required), structure calculation allows the minimum thickness to be respected for the common part Z′ to be determined. The irregularities in the mass 1 may cause this thickness of the zone Z′ to vary locally, but it is easy to ensure that it is never below the predetermined minimum thickness.

In order for the frictional forces to be properly controlled, it is preferable to ensure that there is no direct contact between the first and second stabilizing elements 6, 7.

FIGS. 3 and 4 illustrate an alternative embodiment in which the stabilizing elements 16, 17 are flexible synthetic reinforcements in the form of strips. As an example, these reinforcements are synthetic stabilizing strips based on polyester fibers, such as those sold under the brand name “Freyssissol”.

In the example shown in FIGS. 3 and 4, the strip reinforcements 16 attached to the solid wall are placed along zigzag paths in horizontal planes in the region Z1 of the fill 5. The anchoring members 8 are used for fastening rings or hooks 9 into the mass 1, the strip that will form the reinforcement 16 passing into said rings or hooks. The front side of the strip is advanced towards the facing so as to ensure the sufficient thickness of the force-transmitting zone Z′.

On the facing 3 side, the reinforcements 17 are partly cast in the concrete of the prefabricated elements, thereby ensuring that they are attached to the facing. The cast part of the flexible synthetic reinforcement 17 follows a loop in the prefabricated element 4, and thus has two segments projecting into the region Z2 with the fill 5. These two projecting segments of a reinforcement 17 emerge from the facing 3 at vertically offset positions. One of the reinforcements 16 attached to the solid wall penetrates into the gap separating the two projecting segments of any one reinforcement 17. Another of the reinforcements 16 attached to the solid wall is inserted between the upper segment of a reinforcement 17 embedded in a facing element 4 and the lower segment of the reinforcement 17 embedded in the facing element 4 located just beneath.

It will be appreciated that, within the context of the present invention, the possible arrangements of the reinforcing strips in the gap separating the pre-existing wall 1 from the facing 3 are very numerous. Likewise, all kinds of facings may be used—prefabricated elements in the form of slabs, blocks, etc., wire mesh, window-box, etc. Moreover, it is perfectly conceivable to construct the facing 3 by casting it in situ from special cements or concrete, taking care to connect the stabilizing elements 7, 17 thereto.

The three-dimensional configurations adopted by the stabilizing elements within the fill 5 may also be highly varied: the patterns may be in a form other than a zigzag or a comb; elements 6, 16 and 7, 17 may lie in the same horizontal plane (preferably avoiding mutual contacts); in the common part Z′, the ratio of the density of elements 6, 16 and that of the elements 7, 17 may vary; etc.

To construct a work according to the invention, the procedure may for example be as follows:

-   -   a) the anchoring members 8 are installed on the front face of         the mass to be covered;     -   b) some of the facing elements 4 are put into position so that         the fill material can be introduced to a certain height. The         mounting and positioning of the facing elements may be         facilitated in a known manner by assembling members placed         therebetween;     -   c) a layer of stabilizing elements 6, 16 is installed on the         fill already present. The elements 6 are attached to the         anchoring points 8 in the embodiment according to FIGS. 1 and 2.         In the embodiment according to FIGS. 3 and 4, the reinforcement         strip 16 is laid in a zigzag, making it pass into the rings 9,         and slight tension is exerted at the line where the strip turns         back towards the front, for example by means of a bar placed         along this line and around which the strip is folded at each         point of inflection;     -   d) fill material is introduced over the top of the layer of         stabilizing elements 6, 16 that has just been installed, up to         the next level of stabilizing elements 7, 17 on the rear side of         the facing elements 4. This fill material is compacted         progressively as it is being introduced;     -   e) the stabilizing elements 7, 17 located at said level are put         into place on the fill, tension being exerted thereon;     -   f) fill material is introduced on top of this level and         progressively compacted until the specified level for         introducing stabilizing elements 6, 16 has been reached; and     -   g) steps b) to f) are repeated until the top level of the fill         is reached.

Another embodiment of the invention is illustrated in FIG. 5. The facing elements and the stabilizing elements that are connected thereto, such as those described above, are replaced by geotextile. The geotextile is placed on the ground or on a layer of fill material, and is then folded back on itself towards the solid wall so as to cover and retain a new layer of fill material and to extend into a region Z1 of the fill. The stabilizing elements anchored in the mass pass through the layer of fill material and extend over a region Z2. The regions Z1 and Z2 share a common region Z′, thus allowing the forces between the stabilizing elements anchored into the solid wall and the geotextile layers 27 to be transmitted by the fill material located in this common region.

Each geotextile sheet 30 folded back on itself thus has a front part 24 extending over the front face of the work and forming one portion of the facing 23. The two folded-back layers 27 extend horizontally from this front part 24 into the second region Z2 of the fill in order to form two stabilizing elements for holding the facing in place.

In the advantageous embodiment illustrated in FIG. 6, the facing 33 is formed from a welded wire mesh, and the stabilizing elements 37 consist of metal reinforcements in the form of rolled steel strips. Alternatively, these reinforcements 37 could be replaced with welded mesh strips. The fill may not be homogeneous between the pre-existing wall 31 and the facing 33. For example, it may comprise stones on the front face, retained by the mesh and giving the finished work an attractive appearance, and sand or other filling material between the pre-existing wall and the layer of stones. Alternatively, the sand may extend right up to the wire mesh facing 37, being held in place by a geotextile placed on the rear side thereof.

FIG. 6 also shows that the pre-existing wall 31, onto which the work backs, need not consist of a terrain mass, but also of an artificial structure, for example made of masonry or concrete. 

1. A construction work erected in front of a pre-existing wall, the work comprising a facing erected along a front face of the work, a fill occupying a gap between the facing and the pre-existing wall, and a retention system extending into the fill for keeping the facing in place relative to the pre-existing wall, wherein the retention system comprises first stabilizing elements attached to the pre-existing wall and extending into a first region of the fill, and second stabilizing elements connected to the facing and extending into a second region of the fill, said first and second regions having a common part in which forces are transmitted between the first and second stabilizing elements by the material of the fill.
 2. Construction work of claim 1, wherein the facing comprises prefabricated elements in which the second stabilizing elements are partly embedded.
 3. The construction work of claim 2, wherein the prefabricated elements are made of concrete and the second stabilizing elements comprise flexible synthetic reinforcements each having at least one part cast in the concrete of one of the prefabricated elements.
 4. The construction work of claim 3, wherein the cast part of the flexible synthetic reinforcement follows a loop in the prefabricated element so as to have two segments projecting into the second region of the fill.
 5. The construction work of claim 4, wherein the loop is placed in the prefabricated element so that the two projecting segments of the flexible synthetic reinforcement emerge from the facing into the fill at vertically spaced positions.
 6. The construction work of claim 1, wherein the second stabilizing elements comprise geotextile layers extending into the second region of the fill.
 7. The construction work of claim 6, comprising geotextile sheets folded so as each to have a front part extending over the front face of the work and forming a portion of the facing, and two layers folded back from said front part and extending approximately horizontally into the fill in order to form two of the second stabilizing elements.
 8. The construction work of claim 1, wherein the second stabilizing elements comprise metal reinforcements attached to the facing and extending into the second region of the fill.
 9. The construction work of claim 1, wherein there is substantially no direct contact between the first stabilizing elements and the second stabilizing elements.
 10. The construction work of claim 1, wherein the first stabilizing elements comprise flexible synthetic strips.
 11. The construction work of claim 9, wherein the flexible synthetic strips are placed along zigzag paths in the first region of the fill.
 12. The construction work of claim 1, wherein the second stabilizing elements comprise flexible synthetic strips.
 13. The construction work of claim 1, wherein the facing includes wire mesh.
 14. A method of constructing a work in front of a pre-existing wall, the method comprising the steps of: erecting a facing along a front face of the work, delimiting a volume to be filled; positioning a retention system in a gap between the facing and the wall for holding the facing in position relative to the wall; providing fill material into said gap; and compacting the fill material, wherein the retention system comprises first stabilizing elements attached to the wall and extending into a first region of the fill, and second stabilizing elements connected to the facing and extending into a second region of the fill, said first and second regions having a common part so that, after fill material has been introduced and compacted, forces are transmitted between the first and second stabilizing elements by the fill material located in said common part. 